Magnetic properties of Mn-doped ZnO diluted magnetic semiconductors
Liu Xue-Chao(刘学超)a)b), Zhang Hua-Wei(张华伟)a)b), Zhang Tao(张涛)a), Chen Bo-Yuan(陈博源)a)b), Chen Zhi-Zhan(陈之战)a)†, Song Li-Xin(宋力昕)a), and Shi Er-Wei(施尔畏)a)
a Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China; b Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
Abstract A series of Mn-doped ZnO films have been prepared in different sputtering plasmas by using the inductively coupled plasma enhanced physical vapour deposition. The films show paramagnetic behaviour when they are deposited in an argon plasma. The Hall measurement indicates that ferromagnetism cannot be realized by increasing the electron concentration. However, the room-temperature ferromagnetism is obtained when the films are deposited in a mixed argon-nitrogen plasma. The first-principles calculations reveal that antiferromagnetic ordering is favoured in the case of the substitution of Mn$^{2 + }$ for Zn$^{2 + }$ without additional acceptor doping. The substitution of N for O (N$_{\rm O}^{ - })$ is necessary to induce ferromagnetic couplings in the Zn-Mn-O system. The hybridization between N 2p and Mn 3d provides an empty orbit around the Fermi level. The hopping of Mn 3d electrons through the empty orbit can induce the ferromagnetic coupling. The ferromagnetism in the N-doped Zn-Mn-O system possibly originates from the charge transfer between Mn$^{2 + }$ and Mn$^{3 + }$ via N$_{\rm O}^{ - }$. The key factor is the empty orbit provided by substituting N for O, rather than the conductivity type or the carrier concentration.
Received: 12 July 2007
Revised: 17 October 2007
Accepted manuscript online:
Fund: Project supported by the Shanghai
Nanotechnology Promotion Center (Grant No 0452nm071) and the
National Natural Science Foundation of China (Grant Nos 50702071 and
50772122).
Cite this article:
Liu Xue-Chao(刘学超), Zhang Hua-Wei(张华伟), Zhang Tao(张涛), Chen Bo-Yuan(陈博源), Chen Zhi-Zhan(陈之战), Song Li-Xin(宋力昕), and Shi Er-Wei(施尔畏) Magnetic properties of Mn-doped ZnO diluted magnetic semiconductors 2008 Chin. Phys. B 17 1371
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